1. Field of the Invention
The present invention relates to a method and system for acquiring parameters in process control.
2. Description of the Related Art
In a process control system for monitoring and controlling a process state, various types of adaptive control apparatuses, for example, a sample value control apparatus (Published Unexamined Japanese Patent Application No. 59-167707) having a closed loop autotuning function and an adaptive control apparatus (U.S. Pat. No. 3,798,426) having a pattern recognizing function, are used. In the sample value control apparatus the dynamic characteristics of a process are estimated by inputting an identification signal to a process control system, and control parameters are determined on the basis of the estimated dynamic characteristics.
In such an adaptive control apparatus, when PID (Proportional plus Integral plus Derivative) control parameters used for a PID operation are to be determined, a reference model for defining a process control system and characteristic parameters representing a process state must be set.
Conventionally, characteristic parameters are set by an operator in an adaptive control apparatus before a process control is executed.
Alternatively, in a conventional adaptive control apparatus, a reference model, i.e., design data is stored in advance and is read out as needed so as to obtain characteristic parameters on the basis of the readout design data (Published Unexamined Japanese Patent Application No. 63-138402). Therefore, an operation performed by an operator becomes complicated.
Under these circumstances, a strong demand has arisen for an adaptive control apparatus capable of easily and automatically acquiring various parameters used for a PID operation or the like.